The objectives of this research are: a) to discover enzymes that participate in decay of RNA in Escherichia coli; b) to determine structural genes that govern these enzymes; c) to understand the mechanism of mRNA decay during exponential growth, and ribosomal RNA degradation during starvation. These objectives will be aimed at by: (1) purifying various ribonucleases and their inhibitors and analyzing their mode of action; (2) identifying unknown ribonucleases; (3) isolating bacterial mutants defective in ribonucleases; (4) analyzing genetically strains carrying ribonuclease mutations (location, dominance recessivity); (5) studying the physiology of these mutants especially in RNA metabolism, measuring half life of total mRNA and specific mRNAs during exponential growth, and that of rRNA during carbon starvation, etc; and (6) developing a cell free system where transcription and translation occur simultaneously for the analysis of decay processes.